Optical systems employing compliant electroactive materials

ABSTRACT

The present invention provides optical systems, devices and methods which utilize one or more electroactive films to adjust an optical parameter of the optical device/system.

CROSS REFERENCE OF RELATED APPLICATIONS

This application is a continuation of Ser. No. 12/128,576, filed May 28,2008, which claims the benefit of provisional Application No.60/941,222, filed May 31, 2007, the content of which is incorporatedherein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to adjustable optical systems. Inparticular, it relates to the use of compliant electroactive materialsto construct an optical system having a compact form factor.

BACKGROUND

In conventional optical systems, such as in digital cameras, motors andsolenoids are used as sources of power to displace gears and cams whichact upon optical elements, e.g., lenses, to provide focusing, zoom, andshake prevention. There are many disadvantages to such conventionalsystems—power consumption is high, response times are long, accuracy islimited and space requirements are high.

Advancements in miniaturized technologies have led to high-quality,highly-functioning, light-weight portable devices, and anever-increasing consumer demand for even further improvements. Anexample of this is the development of cellular telephones to include acamera, often referred to as camera phones. While the majority of suchcamera phones employ an all-mechanical lens module having a small formfactor lens, this approach does not offer variable or auto-focusing andzoom capabilities due to the significant number of moving partsrequired. For example, zoom capability requires a combination of lenselements, a motor, and a cam mechanism for transmitting the rotationalmovement of the motor to linear movement in order to adjust the relativepositions of the lenses and an associated image sensor in order toobtain the desired magnification. In addition to the motor and cammechanism, a plurality of reduction gears are is used to accuratelycontrol the relative positioning of the lenses.

Thus, while variable focusing and zoom features are possible within acamera phone and other optical systems having a relatively small formfactor, these features would add substantially to the overall mass ofthese devices. Further, due to the necessity of an extensive number ofmoving components, power consumption is significantly high andmanufacturing costs are increased.

Another approach which reduces the number of parts and mass of anoptical system involves the use of a liquid lens to provide variablefocusing and zoom capabilities. With such liquid lens systems, thevolume of the fluid in the lens may be varied to adjust the focal lengthof the lens. This adjustment can be done without moving the lens, thusit is possible to realize zoom and variable focusing functions without amotor and cam mechanism.

One type of liquid lens system involves the pumping of liquid into andout of a lens chamber to change the curvature of an elastic membranesurface which defines at least a portion of the lens chamber. Thetransfer of fluid into and out of the lens chamber may be accomplishedstrictly by mechanical means, as described in U.S. Pat. Nos. 5,684,637and 6,715,876 and U.S. Patent Application Publication No. 2007/0030573(see, e.g., the embodiment of FIGS. 6A-6C in the latter patentdocument). For these types of lens systems, a complicated control systemis usually needed. Such a control system involves additional movingcomponents to pump and evacuate fluid into the lens chamber, makingthese types of lens systems bulky, expensive and sensitive to vibration.Another variation of such a liquid lens system is described in U.S.Patent Application Publication No. 2007/0030573. This system involvesthe pumping of fluid in and out of a lens chamber having a compliantmembrane, the fluid movement of which is accomplished byelectromechanical means (see, e.g., the embodiment of FIGS. 7-9C of thatpatent document). While the use of an electromechanical actuator mayreduce the number of components required for the liquid lens system, byrequiring the use of a liquid reservoir in addition to the liquidchamber which defines the lens, the bulkiness and mass of the systemremain less than desirable.

Rather than changing the volume of liquid within a lens to effect achange in its shape, another type of liquid lens employs a fixed volumeof liquid. One example of such a system is disclosed in U.S. PatentApplication Publication No. 2006/0164731 in which a sealed liquid lensis attached about its periphery to an impeller structure which impartsmovement and pressure to the fluid filled lens. The impeller structureis made of a number of movable thin plates fastened at regular intervalsaround the lens. The impeller can be operated mechanically orelectro-mechanically to change the diameter of the lens which, in turn,results in a change in radius of the optical surface of the liquid lens.While the size of the lens system may be reduced by the elimination ofan additional liquid reservoir, the number of moving parts required ofsuch an impeller mechanism adds mass to the system and presentsreliability issues.

Other variable-focus liquid lens systems utilizing a fixed volume offluid are known which employ electrowetting principles. Two producers ofliquid lenses, Varioptic of France and Philips Electronics of theNetherlands, have developed such a lens system which employs twoimmiscible (non-mixing) liquids, one an electrically conductive solutionand the other a non-conductive fluid, having different refractiveindices. With the operative placement of electrodes, a voltage appliedthereto modifies the curvature of the interface between the liquids.More specifically, by modulating the electric field across theinterface, its surface tension is caused to change thereby altering itsradius of curvature and focusing light rays passing therethrough toeither a greater or lesser extent. In other words, the shape of the lenscan be made to transition between convergent (concave) and divergent(convex) states and back again. Changing the shape of the lens changesthe curvature radius of the lens, allowing the focal length to bechanged freely. Examples of such liquid lenses are disclosed in U.S.Pat. No. 6,369,954 and U.S. Patent Application Publication Nos.2006/0126190, 2006/0152814 and 2007/0002455. While providing a reducedform factor over the all-mechanical lens positioners, these types ofliquid lens systems have significant drawbacks. Typically, the voltagerequired to effect the desired focal change upon the liquid lens is veryhigh (>250 volts). This results in relatively high power consumptionwhich in turn reduces the potential life of the battery used or,alternatively, requires a larger battery. Further, as this type of lensstructure requires the use of two liquids, it is fairly complicated andexpensive to construct.

Accordingly, it would be advantageous to provide an optical lens systemwhich overcomes the limitations of the prior art. It would beparticularly advantageous to provide such a system whereby thearrangement of and the mechanical interface between a fluidic or liquidlens and its actuator structure were highly integrated so as to reducethe form factor as much as possible. It would be greatly beneficial ifsuch an optical system involved a minimal number of mechanicalcomponents, thereby reducing the complexity and fabrication costs of thesystem. Additionally, it would be highly desirable if such a systemcould effect a relatively large change in the optical properties of itsliquid lens while requiring a relatively small work load, i.e., movementor stroke, on the part of the lens actuator.

SUMMARY OF THE INVENTION

The present invention includes optical systems and devices and utilizingone or more electroactive films to adjust a parameter of the opticaldevice/system. The devices and systems contain one or more opticalelements that may function as lenses having auto-focus and/or zoomcapabilities. The optical elements may also be used to define anaperture or shutter of an optical system which can be adjusted tocontrol the amount of light passing to a separate lens element. In manyvariations, activation of the electroactive film(s) affects a dimensionof the lens element, wherein the dimension is a thickness, diameter orvolume. In certain embodiments, the electroactive film is a component ofthe lens element where, in others, the electroactive film is remotelypositioned from the lens element.

In one variation, the optical elements include a transparent and/ortranslucent membrane and at least one electroactive film disposed aboutat least a portion of the transparent membrane. In certain embodiments,the transparent/translucent membrane is a made of a dielectric materialwhich forms a component of the electroactive film. The membrane may beemployed as a light-passing aperture of a lens device. In other opticalapplications, the membrane defines a fluidic chamber which containsoptical fluid to provide a liquid lens element. The diameter or volumeof the optical fluid may be fixed or variable. In either configuration,the thickness of the lens chamber is variable to adjust the focal lengthof the lens.

The electroactive films used in the subject optical devices and systemsinclude at least one opaque region, e.g., an electroded region, and atleast one transparent and/or tanslucent region, e.g., bare dielectricmaterial, wherein activation of the film changes a surface areadimension of the transparent/translucent region relative to a surfacearea dimension of the opaque region. Such a change in surface area maybe employed to modulate the amount of light passing through thetransparent region. The configuration of the intersection (e.g.,straight, curved, etc.) between the opaque region and the transparentregion may vary from application to application.

An optical system of the present invention includes at least one fluidiclens and at least one electroactive film associated with the at leastone fluid lens, wherein activation of the at least one electroactivefilm affects an optical parameter, e.g., focal length or magnification(zoom), of the fluidic lens. Certain of the subject optical systeminclude a focusing lens component as well as an afocal lens component,wherein at least one of the lens elements includes a fluidic lens. Wherethe afocal lens component utilizes a fluidic lens, the linear positionof the fluidic lens, in certain embodiments, remains constant uponactivation of an electroactive film, with the lens thickness beingadjusted to affect magnification. These systems may include any numberof lenses where any suitable combination of fluidic and solid lenses maybe employed.

The present invention also includes methods for using the subjectdevices and systems. Other methods are directed to using opticalelements of the present invention to focus and/or magnify an image, orto control the amount of light exposed to a lens. In one variation of asubject method of focusing an image using a lens element, the methodincludes providing a fluidic lens comprising a fluid-filled chamberhaving flexible transparent and/or translucent walls and activating anelectroactive film to adjust the thickness of the chamber therebyadjusting a focal length of the fluidic lens. In one particularembodiment, the electroactive film surrounds at least a portion of aperimeter of the chamber, wherein activating the electroactive filmincludes changing a diameter dimension of the chamber. In anotherembodiment, the electroactive film is configured as a pump, whereinactivating the electroactive film comprises pumping fluid to effect achange in the volume of fluid within the chamber. A similar methodinvolves magnifying an image by activating an electroactive film toadjust the thickness of the chamber where the chamber forms an elementof an afocal lens assembly.

These and other features, objects and advantages of the invention willbecome apparent to those persons skilled in the art upon reading thedetails of the invention as more fully described below.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is best understood from the following detailed descriptionwhen read in conjunction with the accompanying schematic drawings, wherevariation of the invention from that shown in the figures iscontemplated. To facilitate understanding of the invention description,the same reference numerals have been used (where practical) todesignate similar elements that are common to the drawings. Included inthe drawings are the following figures:

FIGS. 1A-1C provide exploded, cross-sectional and side views,respectively, of a fluidic optical lens system of the present inventionhaving a fixed volume of fluid, which is employable as anadjustable-focus lens;

FIGS. 2A and 2B provide schematic illustrations of an electroactivepolymer film for use with the optical systems of the present inventionbefore and after application of a voltage;

FIGS. 3A-3C provide planar, cross-sectional and side views,respectively, of the fluidic optical lens system of FIGS. 1A-1C when inan inactive (voltage off) state;

FIGS. 4A-4C provide planar, cross-sectional and side views,respectively, of the fluidic optical lens system of FIGS. 1A-1C when inan active (voltage on) state;

FIG. 5 is a schematic illustration of a lens and the parameters whichaffect the focal length of the lens;

FIG. 6 is a perspective, cross-sectional view of another fluidic opticallens system of the present invention employing a variable volume offluid;

FIG. 7 is an exploded view of another optical system of the presentinvention which is employable as a light control aperture;

FIGS. 8A and 8B provide planar views of the optical system of FIG. 7when in inactive (voltage off) and active (voltage on) states,respectively;

FIG. 9 is an exploded view of another optical system of the presentinvention which is employable as a light control aperture;

FIGS. 10A and 10B provide planar views of the optical system of FIG. 9when in inactive (voltage off) and active (voltage on) states,respectively;

FIG. 11 is an exploded view of another optical system of the presentinvention which is employable as a shutter;

FIGS. 12A and 12B provide planar views of the optical system of FIG. 11when in inactive (voltage off) and active (voltage on) states,respectively;

FIGS. 13A-13C are schematic illustrations of a conventional lens systemin neutral, zoom-out and zoom-in positions, respectively; and

FIGS. 14A-14C are schematic illustrations of a liquid lens system of thepresent invention in the neutral, zoom-out and zoom-in positions,respectively.

DETAILED DESCRIPTION OF THE INVENTION

Before the devices, systems and methods of the present invention aredescribed, it is to be understood that this invention is not limited toa particular form fit or applications as such may vary. Thus, while thepresent invention is primarily described in the context of a variablefocus camera lens, the subject fluidic optical systems may be used inmicroscopes, binoculars, telescopes, camcorders, projectors, eyeglassesas well as other types of optical applications. It is also to beunderstood that the terminology used herein is for the purpose ofdescribing particular embodiments only, and is not intended to belimiting, since the scope of the present invention will be limited onlyby the appended claims.

Referring now to the drawings, and to FIGS. 1A-1C in particular, thereis illustrated a fluidic optical system 2 of the present inventionhaving auto-focus capabilities. Optical system 2 includes electroactivefilms 10, each including a dielectric layer 18, a portion of which issandwiched between two electrode layers 24, with the high voltageelectrodes of each film 10 facing each other and the grounded electrodesfacing outward. Each electroactive film has an electrical contactportion 22 configured for electrical connection to a voltage source (notshown). While a two-ply film configuration is illustrated, a single-plyfilm configuration may also be employed; however, the two-ply structureminimizes the risk of arcing from the high voltage electrode. Where justa single active film is used, a separate non-active film may be neededto fully enclose the fluid chamber. Notwithstanding, there may beinstances where a single film is advantageous. Further, more than twolayers may be employed, for example, where additional force is needed.Configurations having more than two layers of electroactive film mayalso allow for an asymmetrical lens shape where the stiffness of thefilms may vary from each other to enable such asymmetry. The structureand function of the electroactive films are discussed in greater detailbelow with reference to FIGS. 2A and 2B.

Disposed centrally within each film 10 is a transparent and/ortranslucent membrane 14 which, when sealed together about theirperimeters 16 as shown in FIGS. 1B and 1C, define a liquid lens 12. Morespecifically, the sealed membranes 14 define a chamber whichencapsulates an optical fluid. The perimeter 16 of lens 12 is sealed bymeans of an adhesive or the membranes 14 themselves may be made of amaterial that is self-adhesive, e.g., acrylic, silicone, epoxy,cyanoacrylate, etc. The sealed perimeter 16 may solely include membranes14, solely include the electroactive films 10 or include portions ofboth materials. Where sealed perimeter 16 includes electroactive films10, electrodes 24 may be spaced a selected distance from membranes 14 toexpose respective inner annular portions of the dielectric layers 18.Also, the dielectric layer 18 of each film may itself be made of atransparent/translucent material with a central portion defining opticalmembrane 14. Depending on the application at hand, the optical membranemay be transparent without being translucent, or visa versa, or may beboth transparent and translucent. Unless specified otherwise, the termsare used interchangeably herein. In any embodiment, the opticalmembranes and electroactive films collectively define a diaphragm whichis stretched and held about its perimeter by a frame or is otherwisesandwiched between two opposing open frame sides 20. While frame 20 isillustrated having a square configuration, any suitable configurationmay be used.

The composite structure which forms lens system 2 may be referred to asa cartridge. The cartridge, which may have any suitable form fit andsize, may be incorporated into many types of optical devices, such asthose listed above. In some embodiments, it is desirable for thecartridge structure 2 to have a size suitable for use in digitalcameras, cell phone cameras or other small mobile devices. For example,for use in a cell phone, frame 20 may have a width, length or diameterdimension in the range from about 5 to about 15 millimeters and have athickness in the range from about 0.1 to about 1 millimeters; and lens12 may have a diameter in the range from about 1 to about 25 millimetersand a lens radius (when in an inactive condition) in the range fromabout 0.1 to infinity (i.e., nearly flat).

The fluid used within lens 12 may be a liquid or gel, and typically hasa refractive index between about 1.1 and about 3.0, depending on theapplication. The fluid desirably has a viscosity of about 0.1 to about100 centipoises over a temperature range from about −10° C. to about 80°C. Fluids which have these properties and are suitable for use with thepresent invention include but are not limited to silicone oil, e.g.,Bis-Phenylpropyl Dimethicone. The fluid may include dopants, dyes,pigments, particles, nanoparticle and/or chemical elements that serve tomodify the transmissive optical properties of the fluid. For example, itmay be desirable in certain camera applications for the fluid to includeinfrared absorbing particles or pigments that serve as a filter toprevent infrared wavelengths of about 670 nm and greater from beingtransmitted through the fluidic lens while allowing visible wavelengthsto be transmitted generally without loss.

As the transparent/translucent membranes 14 act as optical interfacesdisposed between the lens fluid and the external environment withinwhich the lens 12 is disposed, it is preferable if they have arefractive index matched, i.e., equal or nearly equal, to that of theoptical fluid in order to minimize scattering of light at theirinterface. In many applications, the external environment will be air atstandard atmospheric pressure. However in certain applications it may bedesirable to dispose the lens in other external environments, including,for example, vacuum, pressurized gas, plasma or liquid. At least one andoften both of the two membranes 14 which define the lens chamberpreferably have properties suitable for use in a variable focal lengthlens. Specifically, the membrane material should be sufficientlyelastic, rugged, and transparent to radiation in a frequency range ofinterest, e.g., visible light. Additionally, the membrane materialshould be durable enough to have a lifetime suitable for itsapplication. For example, in a cell phone camera application, themembrane material should have a lifetime of several years and be able tosurvive about one million cycles of operation. Suitable membranematerials for use with the present invention include but are not limitedto silicone-based polymers, such as poly(dimethylsiloxane) (PDMS), or apolyester material, such as PET or Mylar™.

As illustrated in the schematic drawing of FIGS. 2A and 2B,electroactive film 26 comprises a composite of materials which includesa thin polymeric dielectric layer 28 sandwiched between compliantelectrode plates or layers 30, thereby forming a capacitive structure.As seen in FIG. 2B, when a voltage is applied across the electrodes, theunlike charges in the two electrodes 30 are attracted to each other andthese electrostatic attractive forces compress the dielectric layer 28(along the Z-axis). Additionally, the repulsive forces between likecharges in each electrode tend to stretch the dielectric in plane (alongthe X- and Y-axes), thereby reducing the thickness of the film. Thedielectric layer 28 is thereby caused to deflect with a change inelectric field. As electrodes 30 are compliant, they change shape withdielectric layer 28. Generally speaking, deflection refers to anydisplacement, expansion, contraction, torsion, linear or area strain, orany other deformation of a portion of dielectric layer 28. Depending onthe form fit architecture, e.g., the frame in which capacitive structureis employed, this deflection may be used to produce mechanical work. Theelectroactive film 26 may be pre-strained within the frame to improveconversion between electrical and mechanical energy, i.e., thepre-strain allows the film to deflect more and provide greatermechanical work.

With a voltage applied, the electroactive film 26 continues to deflectuntil mechanical forces balance the electrostatic forces driving thedeflection. The mechanical forces include elastic restoring forces ofthe dielectric layer 28, the compliance of the electrodes 30 and anyexternal resistance provided by a device and/or load coupled to film 26.The resultant deflection of the film as a result of the applied voltagemay also depend on a number of other factors such as the dielectricconstant of the elastomeric material and its size and stiffness. Removalof the voltage difference and the induced charge causes the reverseeffects, with a return to the inactive state as illustrated in FIG. 2A.

The length L and width W of electroactive polymer film 26 are muchgreater than its thickness t. Typically, the dielectric layer 28 has athickness in range from about 1 μm to about 100 μm and is likely thickerthan each of the electrodes. It is desirable to select the elasticmodulus and thickness of electrodes 30 such that the additionalstiffness they contribute to the actuator is generally less than thestiffness of the dielectric layer, which has a relatively low modulus ofelasticity, i.e., less than about 100 MPa.

Classes of electroactive polymer materials suitable for use with thesubject optical systems include but are not limited to dielectricelastomers, electrostrictive polymers, electronic electroactivepolymers, and ionic electroactive polymers, and some copolymers.Suitable dielectric materials include but are not limited to silicone,acrylic, polyurethane, flourosilicone, etc. Electrostrictive polymersare characterized by the non-linear reaction of electroactive polymers.Electronic electroactive polymers typically change shape or dimensionsdue to migration of electrons in response to electric field (usuallydry). Ionic electroactive polymers are polymers that change shape ordimensions due to migration of ions in response to electric field(usually wet and contains electrolyte). Suitable electrode materialsinclude carbon, gold, platinum, aluminum, etc. Suitable films andmaterials for use with the diaphragm cartridges of the present inventionare disclosed in the following U.S. Pat. Nos. 6,376,971, 6,583,533,6,664,718, which are herein incorporated by reference.

Referring again to the drawings, FIGS. 3 and 4 illustrate the inactiveand active states, respectively, of the lens system 2 of FIGS. 1A-1C,which states correspond respectively to the inactive and active statesof the electroactive/dielectric film 10 used in the system, asillustrated in FIGS. 2A and 2B. Specifically, in the inactive state, asillustrated in FIGS. 3A-3C, the electroactive film(s) is radiallydilated which results in a corresponding dilation (i.e., inactive stateas illustrated in FIG. 3A-3C) and contraction (i.e., active state asillustrated in FIGS. 4A-4C) of optical membranes 14 and, thus, lens 12.In comparing the inactive and active states of the film, we see that thediameter d of lens 12 is greater in the inactive state than in theactive state (see d₁ in FIG. 3A vs. d₂ in FIG. 4A). As the lens'diameter d decreases, there is a corresponding increase in the thicknesst of lens 12 (see t₁ in FIG. 3B vs. t₂ in FIG. 4B). This effect changesthe focal length or magnification provided by the lens.

Consider a conventional converging lens which has a bi-convex ordouble-convex configuration, as illustrated in FIG. 5, in which bothbounding surfaces have a focusing effect on light-rays passing throughthe lens. With a light source coming from the left (as illustrated), theright side surface of the lens is considered to be the front surface,and the left side surface of the lens is considered to be the backsurface of the lens. As such, C1 is the center of curvature of the frontsurface and C2 is the center of curvature of the back surface. Theradius of curvature R1 of the front surface is the distance between theoptic center O and the point C1. Likewise, the radius of curvature R2 ofthe back surface is the distance between points O and C2. By convention,the radius of curvature of a bounding surface is positive if its centerof curvature lies behind the lens, and negative if its center ofcurvature lies in front of the lens. Thus, in FIG. 5, R1 is positive andR2 is negative. The focal length f of a lens is the distance from theoptical center of the lens to the lens' focal point. For digitalcameras, for example, the focal point is located on the camera's sensor.The lens maker's formula for a thin lens (i.e., lens' thickness d issmall compared to its focal length) correlates a lens' focal length f toits radii of curvature as follows:

${\frac{1}{f} = {\left( {n - 1} \right)\left\lbrack {\frac{1}{R_{1}} - \frac{1}{R_{2}} + \frac{\left( {n - 1} \right)d}{n\; R_{1}R_{2}}} \right\rbrack}},$

where n is the refractive index of the lens material.

While R1, R2 and f are fixed with conventional lenses, a liquid lens ofthe present invention allows the focal length (focus) of the lens to beselectable or tunable. This is accomplished by controlling or regulatingthe amount of voltage applied to the electroactive film 10. As theapplied voltage increases, the radius r of the lens 12 decreases. Sincethe liquid volume of the lens is constant, the radii of curvature R1, R2of the lens increase, which in turn increases the lens' focal length f.Conversely, as the voltage is reduced, the lens radius r increasesthereby decreasing the radii of curvature and decreasing the lens' focallength f. Control electronics integrated with the platform device, e.g.,camera, and interfaced with the lens system can be programmed and usedto control the application of voltage to the electroactive film therebymodulating the focal length of the lens.

The previously described fluidic lens system of the present inventioninvolves a liquid lens having a fixed volume of fluid. The presentinvention also includes fluidic lens systems 40, illustrated in FIG. 6,in which the volume of fluid present within the liquid lens can bevaried in order to tune the focal length of the lens. More particularly,fluid is selectively transferred in and out of the fluidic lens chamber42 and to and from a remote driving chamber 44 via a fluid passage 48.As is explained in greater detail below, this fluid transfer isaccomplished by hydraulic means which provides a pumping actiongenerated by an electroactive component employed as an actuator 46.

The lens portion of the illustrated lens system 40 includes convergingor bi-convex lens. The “front” side (analogous to the same nomenclatureused above with respect to the conventional lens of FIG. 5) is definedby a liquid lens 42 having a fluid chamber defined on its front side bya stretchable, transparent membrane 68 extending across an aperture 64in a bottom or proximal lens housing 66, and defined on a back side by arigid, transparent cover or plate 70. Plate 70 is held between bottom orproximal housing 66 and top or distal lens housing 72. On the oppositeside of transparent plate 70 is a solid/rigid optical lens 76 having aconverging backside which extends into conical aperture 80. Typically,lens 76 is made of polycarbonate or glass but may be made any othersuitable material. The cone angle of aperture 80 dictates the angle atwhich light rays impinge upon plate 70. Positioned between plate 70 andrigid lens 76 is an optical stop 74 which blocks undesirable, i.e.,scattered or random, light rays from passing into liquid lens 42. Aswith conventional lens systems, an infrared (IR) filter 78, set within acutout within the face of top housing 72, is provided on the oppositeside of rigid lens 76. Positioned on the opposite side of membrane 68 isan image sensor 82 which receives the image for digital processing by animage processing chip (not shown). Collectively, these components definethe lens system or “stack” with the stack's focal length beingadjustable by the radius of curvature of membrane 68 of liquid lens 42.

Driving portion of the lens system includes a fluidic driving chamber 44defined on one end by a distal or top housing 58 having side walls. Theproximal or bottom end of chamber 44 is receives a piston 54. A flexiblediaphragm 56 formed of a non-permeable material extends annularly aboutthe distal or chamber end 54 a of piston 54 with its outer edge capturedwithin the chamber housing 58. Diaphragm 56 acts to fluidly seal chamber44 while enabling a bellows-type action to pump fluid in and out of thechamber.

The proximal or driving end 54 b of piston 54 is operatively coupled toelectroactive actuator 46 which acts to drive a piston 54 in and out ofchamber 44. As piston 54 drives against chamber 44, the positivepressure placed in the chamber causes the lens fluid to flow out of thechamber through passageway 48 into lens chamber 42. Conversely, whenpiston 48 is withdrawn, a negative pressure is created within chamber44, thereby causing the system's fluid to be drawn into chamber 44 andout of lens chamber 42.

Here, electroactive actuator 46 has a frustum diaphragm configuration inwhich an electroactive film 52 (as described with respect to FIGS. 2Aand 2B) is held between outer and inner open frame members 50 a, 50 b.Such frustum-type actuators are described in detail in U.S. patentapplication Ser. Nos. 11/085,798, 11/085,804 and 11/618,577, eachincorporated by reference in its entirety. Outer frame member 50 a isheld fixed within actuator housing 60 and inner frame member 50 b is inturn coupled to a proximal end 54 a of piston 54. Diaphragm 56 places abias on piston 54 and on inner frame 50 b in the direction of arrow 62 bsuch that when a voltage is applied to actuator 46, inner frame member50 b is moved further in this biased direction, thereby creating anegative pressure in chamber 44 and drawing fluid from passage 48 in tochamber 44. As the voltage is removed, the reverse motion is experiencedby piston 54 and inner frame 50 b, creating a positive pressure inchamber 44 and forcing fluid into the passage 48 toward the lens chamber42. The amount of voltage applied to actuator 46 may be selectivelycontrolled to modulate the extent of pumping action undergone by thesystem, and thus, finely tuning the volume of fluid present in lenschamber 42. With the radius of lens chamber 42 being fixed, i.e.,defined solely by the diameter of the aperture 64, an increase in thefluid volume within the lens will cause membrane 68 to extend radiallyoutward toward image sensor 82, thereby changing the radius of curvatureof liquid lens 42 and, thus, the focal length of the lens stack.

Turning now to FIG. 7, there is illustrated another optical system 90 ofthe present invention functions similarly to the eye's iris in that thediameter of the aperture defined by the iris is adjusted to regulate theamount of light passing therethrough. Optical system 90 includes atwo-ply transparent/translucent membrane 92 which defines thelight-passing aperture. Extending radially outward from at least aportion of each membrane 92 is an electroactive film including adielectric layer 94, a portion of which is sandwiched between twoelectrode layers 96. As with the auto-focus lens system described above,a single film layer may alternatively be employed. The structure andfunction of the iris' electroactive films is as discussed above withrespect to FIGS. 2A and 2B. In the illustrated embodiment, the electrodelayers 96 are provided annularly about their associated membranes 92.Each electroactive film has an electrical contact portion 98 configuredfor electrical connection to a voltage source (not shown). Collectively,the optical membranes and electroactive film(s) define a diaphragm whichis stretched and held about its perimeter by a frame or is otherwisesandwiched between two opposing open frame sides 100. While frame 100 isillustrated having a square configuration, any suitable configurationmay be used. This composite structure, which may also be referred to asa cartridge, as with the subject lens systems, may have any suitableform fit and size, and may be incorporated into many types of opticaldevices.

FIGS. 8A and 8B illustrate the inactive and active states, respectively,of optical system 90, which states correspond respectively to theinactive and active states of the electroactive film used in the system,as illustrated in FIGS. 2A and 2B, respectively. In the inactive state,as illustrated in FIG. 8A, the electroactive film(s) is radially dilatedwhich results in a corresponding dilation of iris aperture 92, which inturn allows more light to pass therethrough. In the active state, asillustrated in FIG. 8B, the electroactive film(s) is radiallycontracted, which restricts or reduces the amount of light that can passtherethrough. In comparing the inactive and active states of the film,we see that the radius r of iris 92 is greater in the inactive statethan in the active state (see r₁ in FIG. 8A vs. r₂ in FIG. 8B).Controlling the extent to which the radial dimension of iris 92 isdilated or contracted correspondingly adjusts the amount of lightpassing through the aperture. As such, system 90 is usable and usefulwith any lens system in which the amount of light impinging upon thelenses affects the image. For example, optical system 90 may be employedwith either of the fixed-volume (FIGS. 1, 3 and 4) or variable-volume(FIG. 6) liquid lens systems of the present invention, as well as withconventional lens systems. In either context, adjustable aperture 90 ispositioned on the “back” side of the lenses such that the amount oflight impinging on the lenses is controlled. If a filter, such as IRfilter 78 of the variable-volume lens system of FIG. 6, is employed,iris 90 may be positioned on either side of the filter.

FIGS. 9, 10A and 10B illustrate another iris or aperture system 110 ofthe present invention. Aperture 110 is similarly constructed to aperture90 of FIGS. 7 and 8, having two electroactive films 112, each having adielectric layer 116 sandwiched between two electrode layers 114, withthe high voltage electrodes facing towards each other. Frame sides 120hold the films together in a cartridge structure while providing an openspace or passage defining the working area of the subject apertures. Adifference between aperture 110 and aperture 90 is that each of thedielectric polymer layers 116 has a cut-out 118 to define an openingtherethrough. The cut-out is preferably circular, leaving behind anannular portion of dielectric material 116 which is opaque rather thantransparent. A centrally positioned, opaque polymer disc 122 is providedon each film layer 112 and a frame side 120. Disc 122 has a centralopening or aperture 124 which lies within cut-out 118 and through whichlight passes when operatively employed within an optical system. Theouter perimeter of disc 122 may be sealed to the inner perimeter ofdielectric film 116 by means of an adhesive or the two components may bemade of materials that are self-adhesive, e.g., acrylic, silicone, etc.With an annular configuration, disc 122 evenly distributes the tensionon layer 116. Additionally, the two components act to pre-strain eachother. The same type of polymer may be used for dielectric layer 116 anddisc 122; however, the polymer types need not be the same. In eithercase, disc 122 is typically thicker and has a higher pre-strain thandielectric layer 116, making it “stronger” and stiffer than dielectriclayer 116.

FIGS. 10A and 10B illustrate the inactive and active states,respectively, of optical system 110, which states correspondrespectively to the inactive and active states of the electroactive filmused in the system, as illustrated in FIGS. 2A and 2B, respectively. Inthe inactive state, as illustrated in FIG. 10A, the electroactivefilm(s) and dilatable disc(s) 116 are radially dilated which results ina corresponding dilation of disc aperture or opening 124, which in turnallows more light to pass therethrough. In the active state, asillustrated in FIG. 10B, the electroactive film(s) and dilatable disc(s)116 are radially contracted which results in a corresponding contractionof disc aperture or opening 124, which in turn restricts or reduces theamount of light that can pass through aperture 124. In comparing theinactive and active states of the film, we see that the radius r ofopening 124 is greater in the inactive state than in the active state(see r₁ in FIG. 10A vs. r₂ in FIG. 10B). Controlling the extent to whichthe radial dimension of opening 124 is dilated or contractedcorrespondingly adjusts the amount of light passing through it. As such,system 110 is also usable and useful with either of the fixed-volume(FIGS. 1, 3 and 4) or variable-volume (FIG. 6) liquid lens systems ofthe present invention, as well as with conventional lens systems.

FIGS. 11, 12A and 12B illustrate shutter system 130 of the presentinvention which also utilizes electroactive films. Shutter 130 includestwo electroactive film layers 132 a and 132 b. Each electroactive film132 a, 132 b is comprised of a dielectric transparent/translucentpolymer film 134 and an electrode pair 136 with the two electrodesdisposed on opposite sides of each polymer film 134, the high voltageelectrodes facing inward toward each other. The electrode pair 136 adisposed on electroactive film 132 a is positioned at a bottom or lowerportion of the rectangularly-shaped film, while electrode pair 136 b isdisposed on a top or upper portion of electroactive film 136 b whichalso has a rectangular shape. Three open frames with matching cut-outportions are employed to operatively hold films 132 a, 132 b. Two outerframes 138, 139 sandwich the films together while a third frame 140 ispositioned between the two films. With the cartridge fully assembled, asillustrated in FIG. 12A, the front or centrally disposed edges 142 a,142 b of the respective active areas, i.e., the electroded areas, arespaced a short distance apart when in their inactive states. With theinterposed third frame 140, unlike the previously described cartridges,films 132 a, 132 b are not physically coupled together, however they maystill be electrically coupled together and powered by the same powersource. Further, the active portion of each film is held and stretchedsubstantially uniformly on only these three sides, i.e., the frames holdthese sides substantially close to their perimeters. As the front edges142 a, 142 b, respectively, of each of the active areas is held intension by the frame ends furthest from the edges, i.e., frame ends 138a, 139 a, 140 a for active area 136 a and frame ends 138 b, 139 b, 140 bfor active area 136 b, the tension or pre-strain placed on the frontedges is less than that placed on the other edges of the active area. Assuch, the primary movement of the respective active regions uponactuation is along their front edges 142 a, 142 b.

FIGS. 12A and 12B illustrate the inactive and active states,respectively, of shutter system 130, which states correspondrespectively to the inactive and active states of the electroactive filmused in the system, as illustrated in FIGS. 2A and 2B, respectively. Inthe inactive state, as illustrated in FIG. 12A, the front edges 142 a,142 b of the respective active areas of electroactive films 132 a, 132 bare spaced a distance apart thereby defining a transparent, open spacebetween the active areas. This spacing is sufficient to expose the lensand/or aperture (in phantom) 135 that would be positioned behind thefilms. When the films are activated, as illustrated in FIG. 12B, thefront edges 142 a, 142 b of the respective active areas are caused toexpand linearly toward each other. When fully actuated, edges 142 a and142 b overlap each other to the extent necessary to cover the lensand/or aperture (not shown). In the context of a camera, for example,the shutter is open (i.e., the films are inactive) when it is desirousto expose the image sensor to light, typically not more than about 30ms. Shutter system 130 is usable and useful with any of the lens andaperture systems of the present invention, as well as with conventionaloptical systems.

While two films are used in the illustrated shutter embodiment, a singlefilm or more than two films may be employed. For example, several or aplurality of films collectively defining an impeller configuration maybe used. Further, the one or more shutter films may have any suitablenumber and shapes of opaque (electroded) and transparent/translucentportions. Because the shutter's function is to be in either one of twodiscrete states, i.e., open or closed, the variability of the opencircular film configurations of the above-described aperture systems, isnot necessary. However, a circular configuration (i.e., where the opaqueelectrode portion defines a circular transparent portion) maybe employedwhere the closed position of the aperture is such that area of thetransparent/translucent portion is substantially negligible. In anycase, the surface area of the opaque portion(s) of the electroactivefilm when expanded or extended upon activation covers the light-passingaperture.

The present invention also provides optical systems with zoomcapabilities. While more complex zoom lenses may have upwards of thirtyindividual lens elements, and multiple parts to move the lens elements,most conventional zoom lens systems follow the same basic design, asillustrated in FIGS. 13A-13C. Generally, a conventional zoom lens stack150 consists of two parts: a focusing lens 152 similar to a standard,fixed-focal-length photographic lens preceded by an afocal zoom system154, which does not focus the light, but alters the size of a beam oflight 155 traveling through it, and thus the overall magnification ofthe lens system. Afocal zoom system 154 consists of an arrangement offixed and movable lens elements. In zoom lens system 150, the afocalsystem 154 consists of two positive (converging) lenses of equal focallength 154 a, 154 c with a negative (diverging) lens 154 b between themand having an absolute focal length less than half that of the positivelenses. Lenses 154 a, 154 c are fixed, but lens 154 b can be movedaxially along the longitudinal axis of the lens stack 150. In a morecomplex arrangement, lens 154 a may also be movable. Movement of thelens(es) is usually performed by a complex arrangement of gears and camsin the lens housing, although some modern zoom lenses usecomputer-controlled servos to perform this positioning.

When diverging lens 154 b is positioned equidistance between converginglenses 154 a, 154 c (see FIG. 13A), the system is neutral, i.e., thecross-sectional dimension of the collimated beam of light 155 enteringthe system remains substantially constant. In other words, there is nomagnification of the image on which focusing lens 152 is focused. Asdiverging lens 154 b moves towards the back B of the stack (see FIG.13B), i.e., zooms in, the magnification of the system increases.Conversely, as diverging lens 154 b moves towards the front F of thestack (see FIG. 13C), i.e., zooms out, the magnification of the systemdecreases.

The focal length of a zoom lens is given as a range of two figures, thefirst is the focal length (mm) when the zoom is not being used and thesecond is the focal length (mm) when the zoom is fully extended. Thezoom ratio, then, is the ratio of the focal length with the zoom fullyextended to the focal length when the zoom is not being used. A typicalconventional digital camera has a focal length of 35 mm without zoom anda focal length of 105 mm with zoom. Thus, the camera's zoom ratio isabout 3×. In order to increase a camera's zoom ratio, either largerlenses or more of them must be used. This in turn requires more spacefor the lenses as well as for the cams and gears needed to move thelenses.

Moreover, as the magnification of a zoom lens changes, it is necessaryto compensate for any movement of the focal plane (commonly referred toas “shake”) to keep the focused image sharp. In conventional lenssystems, this compensation may be done by mechanical means, i.e., movingthe complete lens assembly as the magnification of the lens changes, oroptically, i.e., arranging the position of the focal plane to vary aslittle as possible as the lens is zoomed.

It is for at least the aforementioned space requirements and theconsequential weight added to an optical system that zoom capabilitiesare not provided in very compact optical systems such as cell phonecameras. The present invention overcomes these shortcomings ofconventional optical zoom systems by utilizing one or more of thesubject liquid lenses in a lens stack assembly to provide zoomcapabilities with reduced space requirements and with less weight addedto the overall system or device.

Referring now to FIGS. 14A-14C, there is shown a schematicrepresentation of an optical lens system or stack 160 of the presentinvention having zoom capabilities. Lens system 160 includes focusinglens 162 at a back end B of lens stack 160 and an afocal zoom system 164proximal thereto. Unlike the conventional afocal zoom systems discussedabove, zoom system 164 does not include any moving lens elements, i.e.,all of the lenses are fixed as their movement is not required to effectimage magnification. Notwithstanding, it is contemplated that theelectroactive film actuators disclosed in the patent referencesincorporated herein may be employed to linearly translate the lenselements to affect a zoom effect.

In the illustrated embodiment, afocal zoom system 164 consists of twopositive (converging) lenses 164 a, 164 c and a negative (diverging)lens 164 b therebetween. One or more of the afocal lenses may be aliquid lens, such as the liquid lens of FIGS. 1A-1C. In one variation ofthe invention, at least two of the afocal lenses are liquid lenses. Inone embodiment of the latter variation, converging lenses 164 a and 164c are liquid lenses and diverging lens 164 b is a conventional solidlens. However, any two (or more) of the afocal lenses may have a liquidconfiguration. Either a liquid lens of the present invention or aconventional solid lens may be used for focusing lens 162, which isconverging on its front end. Alternatively, afocal lens 164 c andfocusing lens 162 may be integrated into a single converging lens, whichmay be liquid or solid; however, image quality may be compromised.

As illustrated in FIGS. 14B and 14C, no translational (axial) movementof any of the afocal lenses, including diverging lens 164 b, isnecessary to vary magnification of lens stack 160, whether zooming in(as in FIG. 14B) or zooming out (as in FIG. 14C). Instead, thethicknesses (t_(a), t_(b), t_(c)) of the respective liquid lenses may beadjusted. The change in lens thickness may be effected by varying thediameter/radius of the lens, as with the fixed volume liquid lens systemof FIGS. 1A-1C, or by varying the volume of liquid within the lenschamber, as with the variable volume liquid lens system of FIG. 6, wherethe form fit of the liquid lens systems may be varied to accommodate azoom lens stack. With either configuration, when the afocal lens stack164 is in the neutral configuration (no magnification) illustrated inFIG. 14A, each of the afocal lenses as a selected thickness t_(a),t_(b), t_(c), respectively. To zoom out from the neutral configuration(see FIG. 14B), the thickness t_(a) of lens 164 a is reduced and thethickness t_(b) of is increased proportionately. To zoom in from theneutral configuration (see FIG. 14C), the thickness t_(a) of lens 164 ais increased and the thickness t_(c) of is decreased proportionately. Asthe thickness t_(b) of diverging lens 164 b in this embodiment remainsconstant in any zoom configuration (neutral, zoom out, zoom in), a solidlens having a fixed thickness may be readily employed in lieu of aliquid lens. It is to be understood, however, that any combination ofliquid and solid lenses, and less or more than three afocal lenses maybe employed with the optical zoom systems of the present invention.

In any case, without the need to linearly translate any of the lenses(or with only a minimum number of linearly translatable lenses) of theafocal lens assembly to effect magnification, the required spacingbetween the respective lenses is reduced and the space that wouldotherwise be required for the cam mechanisms for translating the lensesis eliminated. The greater flexibility in space requirements increasesthe theoretical focal length of the lens assembly when in the zoom mode.Thus, depending on the size (thickness) of the lenses, the percentage ofthose that have adjustable thicknesses, and the spacing placed betweenthem, the zoom ratio of the subject optical systems may be made to begreater than 3×, and even greater than 10× or more.

Methods of the present invention associated with the subject opticalsystems, devices, components and elements are contemplated. For example,such methods may include selectively focusing a lens on an image,selectively adjusting light exposed to a lens or magnifying an imageusing a lens assembly. The methods may comprise the act of providing asuitable device or system in which the subject inventions are employed,which provision may be performed by the end user. In other words, the“providing” (e.g., a pump, valve, reflector, etc.) merely requires theend user obtain, access, approach, position, set-up, activate, power-upor otherwise act to provide the requisite device in the subject method.The subject methods may include each of the mechanical activitiesassociated with use of the devices described as well as electricalactivity. As such, methodology implicit to the use of the devicesdescribed forms part of the invention. Further, electrical hardwareand/or software control and power supplies adapted to effect the methodsform part of the present invention.

Yet another aspect of the invention includes kits having any combinationof devices described herein—whether provided in packaged combination orassembled by a technician for operating use, instructions for use, etc.A kit may include any number of optical systems according to the presentinvention. A kit may include various other components for use with theoptical systems including mechanical or electrical connectors, powersupplies, etc. The subject kits may also include written instructionsfor use of the devices or their assembly. Such instructions may beprinted on a substrate, such as paper or plastic, etc. As such, theinstructions may be present in the kits as a package insert, in thelabeling of the container of the kit or components thereof (i.e.,associated with the packaging or sub-packaging) etc. In otherembodiments, the instructions are present as an electronic storage datafile present on a suitable computer readable storage medium, e.g.,CD-ROM, diskette, etc. In yet other embodiments, the actual instructionsare not present in the kit, but means for obtaining the instructionsfrom a remote source, e.g. via the Internet, are provided. An example ofthis embodiment is a kit that includes a web address where theinstructions can be viewed and/or from which the instructions can bedownloaded. As with the instructions, this means for obtaining theinstructions is recorded on suitable media.

As for other details of the present invention, materials and alternaterelated configurations may be employed as within the level of those withskill in the relevant art. The same may hold true with respect tomethod-based aspects of the invention in terms of additional acts ascommonly or logically employed. In addition, though the invention hasbeen described in reference to several examples, optionallyincorporating various features, the invention is not to be limited tothat which is described or indicated as contemplated with respect toeach variation of the invention. Various changes may be made to theinvention described and equivalents (whether recited herein or notincluded for the sake of some brevity) may be substituted withoutdeparting from the true spirit and scope of the invention. Any number ofthe individual parts or subassemblies shown may be integrated in theirdesign. Such changes or others may be undertaken or guided by theprinciples of design for assembly.

Also, it is contemplated that any optional feature of the inventivevariations described may be set forth and claimed independently, or incombination with any one or more of the features described herein.Reference to a singular item, includes the possibility that there areplural of the same items present. More specifically, as used herein andin the appended claims, the singular forms “a,” “an,” “said,” and “the”include plural referents unless the specifically stated otherwise. Inother words, use of the articles allow for “at least one” of the subjectitem in the description above as well as the claims below. It is furthernoted that the claims may be drafted to exclude any optional element. Assuch, this statement is intended to serve as antecedent basis for use ofsuch exclusive terminology as “solely,” “only” and the like inconnection with the recitation of claim elements, or use of a “negative”limitation. Without the use of such exclusive terminology, the term“comprising” in the claims shall allow for the inclusion of anyadditional element—irrespective of whether a given number of elementsare enumerated in the claim, or the addition of a feature could beregarded as transforming the nature of an element set forth n theclaims. Stated otherwise, unless specifically defined herein, alltechnical and scientific terms used herein are to be given as broad acommonly understood meaning as possible while maintaining claimvalidity.

1. An optical device comprising: a transparent/translucent membrane; andat least one electroactive film comprising a dielectric layer and twoelectrode layers, wherein at least a portion of the dielectric layer issandwiched between the electrodes; wherein activation of the at leastone electroactive film affects a dimension of the transparent membrane.2. The optical device of claim 1, wherein the dielectric layer definesthe transparent/translucent membrane.
 3. The optical device of claim 1,wherein the dimension is a diameter or a thickness.
 4. The opticaldevice of claim 1, wherein the transparent/translucent membrane istwo-ply.
 5. The optical device of claim 4, wherein the two-plytransparent/translucent membrane defines a chamber therebetween, thedevice further comprising an optical fluid contained within the chamber.6. The optical device of claim 5, wherein the affected dimension is thethickness of the chamber.
 7. The optical device of claim 6, wherein thechamber has a variable diameter and a fixed volume.
 8. The opticaldevice of claim 6, wherein the chamber has a fixed diameter and avariable volume.
 9. An optical system comprising: at least one fluidiclens; and at least one electroactive film associated with the at leastone fluid lens, wherein activation of the at least one electroactivefilm affects an optical parameter of the fluidic lens.
 10. The opticalsystem of claim 9, wherein the optical parameter is focal length. 11.The optical system of claim 10, wherein the at least one fluidic lenscontains a fixed volume of fluid
 12. The optical system of claim 10,wherein the at least one fluidic lens contains a variable volume offluid.
 13. The optical system of claim 12, further comprising hydraulicmeans to vary the volume of optical fluid with the chamber.
 14. Theoptical system of claim 13, wherein the hydraulic means comprises anelectroactive film.
 15. The optical system of claim 10, whereinactivation of the at least one electroactive film affects a diameterdimension of the fluidic lens.
 16. The optical system of claim 10,wherein a diameter dimension of the fluidic lens is unaffected byactivation of the at least one electroactive film.
 17. The opticalsystem of claim 9, wherein the optical parameter is magnification. 18.The optical system of claim 17, wherein a linear position of the atleast one fluidic lens remains constant upon activation of the at leastone electroactive film.
 19. The optical system of claim 10, whereinactivation of the at least one electroactive film affects a dimension ofthe at least one fluidic lens.
 20. An optical system comprising: afocusing lens element; and an afocal lens element positioned relative tothe focusing lens; wherein at least one of the lens elements comprisesat least one fluidic lens and at least one electroactive film associatedwith the at least one fluidic lens for adjusting an optical parameter ofthe system.
 21. The optical system of claim 20, wherein the afocal lenselement comprises an assembly of lenses wherein one of such lenses is afluidic lens and activation of the at least one electroactive filmadjusts the magnification of the afocal lens assembly.
 22. The opticalsystem of claim 21, wherein the position of the afocal lens assemblyrelative to the focusing lens remains constant upon activation of the atleast one electroactive film.
 23. The optical system claim 21, whereinthe afocal lens assembly further comprising at least two other lenselements wherein the at least one fluid lens is positioned in betweenthe two other lens elements.
 24. A method of focusing an image using alens element, the method comprising: providing a fluidic lens comprisinga fluid-filled chamber having flexible transparent/translucent walls;activating an electroactive film to adjust the thickness of the chamberthereby adjusting a focal length of the fluidic lens.
 25. The method ofclaim 24, wherein the electroactive film surrounds at least a portion ofa perimeter of the chamber, wherein activating the electroactive filmcomprises changing a diameter dimension of the chamber.
 26. The methodof claim 24, wherein the electroactive film is configured as a pump,wherein activating the electroactive film comprises pumping fluid toeffect a change in the volume of fluid within the chamber.
 27. A methodof magnifying an image using a lens element, the method comprising:providing an afocal lens assembly comprising a fluid-filled chamberhaving flexible walls; activating an electroactive film to adjust thethickness of the chamber.
 28. The method of claim 27, wherein theelectroactive film surrounds at least a portion of a perimeter of thechamber, wherein activating the electroactive film comprises changing adiameter dimension of the chamber.
 29. An optical device comprising: atleast one electroactive film comprising at least one opaque region andat least one transparent region, wherein activation of the at least oneelectroactive film changes a surface area of the transparent/translucentregion relative to a surface area of the opaque region, wherein suchchange modulates the amount of light passing through the at least onetransparent/translucent region.
 30. The optical device of claim 29,wherein the at least one opaque region of the film comprises at leastone electrode layer.
 31. The optical device of claim 29, wherein the atleast one transparent/translucent region of the film comprises adielectric material.
 32. The optical device of claim 29, wherein theintersection between the at least one opaque region and the at least onetransparent/translucent region defines a straight line when the at leastone electroactive film is inactive.
 33. The optical device of claim 29,wherein the intersection between the at least one opaque region and theat least one transparent/translucent region defines a curved line whenthe at least one electroactive film is inactive.